docs: def rdf_source(self, aformat="turtle"):
  		"""
  		Serialize graph using the format required
  		"""
  		if aformat and aformat not in self.SUPPORTED_FORMATS:
  			return "Sorry. Allowed formats are %s" % str(self.SUPPORTED_FORMATS)
  		if aformat == "dot":
  			return self.__serializedDot()
  		else:
  			# use stardard rdf serializations
  			return self.rdflib_graph.serialize(format=aformat)